In numerous electronic equipments, an electronic component is surface mounted on various circuit substrates such as printed board, and a filter circuit configured by passive elements such as capacitor element or inductor, and resistor is arranged at a predetermined terminal pin of the electronic component to reduce high frequency noise generated from a power supply line etc. of the electronic component.
Conventionally, a circuit configuration in which one of the electrode terminals of a chip capacitor element is connected to the terminal pin and the other electrode terminal is grounded is made on the same plane as the circuit substrate mounted with the electronic component. In such configuration, however, a region for mounting the chip capacitor element is also necessary at the periphery of the electronic component, whereby a mounting density of the circuit substrate cannot be enhanced. Thus, review is made in mounting a filter circuit for preventing noise of the electronic component on the circuit substrate at as small as possible mounting area.
For instance, FIG. 21 is a view showing an example in which a conventional noise filter is accommodated and integrated with a connector. In the prior art example, a configuration in which plug inserting chamber 272 to be inserted with a plug and, at a rear part thereof, accommodating chamber 273 are arranged at housing 271 of connector 270, where filter 280 configured by capacitor element arrays etc. is accommodated in accommodating chamber 273 and integrated is shown. In housing 271, terminal 274A, which is an extended portion of terminal pin 274 projecting to accommodating chamber 273, and one end 275A of terminal 275 to be connected to a print wiring are arranged facing each other in accommodating chamber 273, and ground electrode 276 is arranged on both sides in the short side direction.
Input side external electrode 282, output side external electrode 284, and ground electrode 286 are arranged at filter 280, and the capacitor element (not shown) of a number corresponding to terminal pin 274 is formed inside. Filter 280 is accommodated in accommodating chamber 273 with upper and lower surfaces sandwiched by terminal 274A of terminal pin 274 and one end 275A of terminal 275, and both sides sandwiched by ground electrodes 276.
An example in which the filter circuit for preventing noise is integrated with the connector to reduce the mounting area on the circuit substrate according to the above configuration is disclosed in Unexamined Japanese Patent Publication No. 6-20746 (hereinafter referred to as “patent document 1”).
The configuration includes a male connector with a plurality of terminal pins and a metal shell positioned so as to surround the terminal pins and connected to ground potential, and a sheet-type noise filter which can be attached to a concave part of the shell by penetrating the terminal pins is disclosed in Unexamined Japanese Patent Publication No. 11-329609 (hereinafter referred to as “patent document 2”). The sheet-type noise filter has a noise removing circuit arranged on an elastically deformable thin insulating sheet, and has a shape in which a plurality of holes for penetrating the terminal pins is formed, and a plurality of projection strips which elastically abut an inner surface of the shell when attached to the concave part of the shell is projecting out from an outer peripheral edge.
In the connector equipped with a plurality of terminal pins, a configuration of arranging a sheet-type noise absorbing element in a region surrounded by such terminal pins and connecting the same to a circuit substrate is disclosed in Unexamined Japanese Patent Publication No. 2004-335946 (hereinafter referred to as “patent document 3”). The sheet-type noise filter has a noise removing circuit arranged on an elastically deformable thin insulating sheet, and connected to a circuit substrate with a connector to be given a noise removing function. According to such configuration, the mounting area of the circuit substrate can be reduced since the insulating sheet formed with the noise filter circuit is arranged between the connector and the circuit substrate.
However, in patent document 1, the filter including the capacitor element array has a configuration of being arranged in a vertical direction with respect to the circuit substrate surface, and thus is very difficult to have a lower height and is difficult to be used in mobile electronic equipments such as mobile phone where reduction of a thickness is especially demanded.
In patent document 2, the mounting configuration is simple as it is simply used by inserting the sheet-type noise filter to the terminal pins and inserting the female connector to the terminal pins. However, elements such as capacitor element might get damaged when being inserted to the terminal pin. In order to prevent this, a sufficiently thick sheet, which is less likely to deform even by a load applied in time of insertion, must be used. Furthermore, since the connector of such configuration is not a surface mounting type, lowering of height is difficult similar to the case of patent document 1.
Furthermore, in patent document 3, a thin noise filter with respect to the connector is configured by arranging the sheet-type noise filter immediately below the connector. However, the single body of the capacitor element is merely electrically inserted between the connector and the circuit substrate, and thus a frequency filter demanded in the circuit configuration is difficult to form.
Moreover, if elements such as capacitor element and resistor element are formed on the same plane in advance to form a circuit in order to configure the sheet-type noise filter, the manufacturing process of the sheet-like noise filter becomes complicating, and cost tends to increase due to lowering in yield rate.